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From "Xiao-Feng Li" <xiaofeng...@gmail.com>
Subject Re: Re: Re: [general] features
Date Thu, 08 Jan 2009 08:07:35 GMT
On Thu, Jan 8, 2009 at 4:01 PM, Ian Rogers <rogers.email@gmail.com> wrote:
> 2009/1/8 Xiao-Feng Li <xiaofeng.li@gmail.com>
>
>> On Thu, Jan 8, 2009 at 12:52 AM, Rui Chu <rchu@nudt.edu.cn> wrote:
>> > Ignoring the native APIs, can we take the heap, stack, byte codes, TLS
>> and other mgmt metadata in a JVM as an status information?  Can we store the
>> status in a disk file, and restore them later to perform an approximate
>> "hibernate"? Maybe it is rather simple and coarse, while it would be
>> attractive even when it only works for a few simple applications.
>> > After all, JVM is also a simple machine model rather than a full layered
>> OS and system hardware...
>>
>> I actually had made this work with another simpler JVM implementation.
>> It should be not difficult to achieve with Harmony.
>>
>> Thanks,
>> xiaofeng
>
>
> There is a similar project using Jikes RVM:
>
> http://www.agentgroup.unimore.it/didattica/curriculum/raffaele/mobility_work.html
>
> As I understand it they are using a pre version 3 Jikes RVM and so don't yet
> have the option of using the Harmony class library.

I guess it is more straightforward to implement such feature with a
JVM written in Java like JikesRVM, because its boot-image has already
part of the functionality. To add running application support is only
an extension?

Thanks,
xiaofeng

> Regards,
> Ian
>
>> ------------------
>> > Rui Chu
>> > 2009-01-08
>> >
>> > -------------------------------------------------------------
>> > 发件人:Jack Cai
>> > 发送日期:2009-01-07 17:27:07
>> > 收件人:dev
>> > 抄送:
>> > 主题:Re: Re: [general] features
>> >
>> > So to quickly answer your questions -
>> >
>> > #2: No, neither SUN JVM nor Harmony JVM support such "hibernate"
>> operation.
>> > JVM does not have an abstract Hardware level, even though it does manage
>> the
>> > memory and threads for a running process. So it is not a "real" operating
>> > system. It accesses resources by calling the hosting OS's native APIs
>> > directly. As a result, it's not as easy to hibernate a JVM as we do with
>> > Windows, VMWare, etc.
>> >
>> > #3: Yes, sandbox is the built-in Java security model. You can achieve
>> what
>> > you described through a customized SecurityManager. You can search google
>> to
>> > find enough to read.
>> >
>> > - Jack
>> >
>> > 2009/1/7 Rui Chu <rchu@nudt.edu.cn>
>> >
>> >> Thank you, Xiaofeng.
>> >>
>> >> About Java Isolation, I am not sure whether SUN JVM implements it. If
>> not,
>> >> maybe the benefit of Isolation is still trivial to motivate the guys in
>> SUN,
>> >> although it looks nice in the proposal.
>> >>
>> >> About the second question, as you know, VMWare, as well as other
>> >> system-level virtual machines, can suspend the guest operating system
>> when
>> >> you press the 'suspend' button. You can also resume it later, or even
>> resume
>> >> it in another host system. This feature really looks charming in my
>> mind.  I
>> >> think JVM can also support it more easily because JVM has a relative
>> simpler
>> >> architecture then the system-level VMs (although it is still complex). I
>> >> wonder if current Harmony or SUN JVM could do that.
>> >>
>> >> The sandbox in my third question does not only mean Applet. In my
>> vision,
>> >> it should support general java applications. The execution of the
>> >> application is monitored and restricted, especially the operations
>> through
>> >> JNI. For example, the java application cannot  access the native file
>> system
>> >> with the same privilege of JVM, and it can only accesses a virtualized
>> file
>> >> system instead. Is there any project or plan in Harnony or SUN JVM to do
>> >> that?
>> >>
>> >> Thanks again, Xiaofeng. I have read some documents and source codes. But
>> >> the souce codes can only prove what has been done in Harmony, while
>> cannot
>> >> tell me what is still not implemented. :)  If possible, I want to
>> continue
>> >> to discuss this topic with you. Waiting for you kind response. Anybody
>> else
>> >> want to join the topic are also appreciated.
>> >>
>> >> ------------------
>> >> Rui Chu
>> >> 2009-01-07
>> >>
>> >> -------------------------------------------------------------
>> >> 发件人:Xiao-Feng Li
>> >> 发送日期:2009-01-07 08:35:56
>> >> 收件人:dev
>> >> 抄送:
>> >> 主题:Re: [general] features
>> >>
>> >> Rui, thanks for your interests in Harmony. My personal opinions are
>> >> inlined below.
>> >>
>> >> On Wed, Jan 7, 2009 at 12:39 AM, Rui Chu <rchu@nudt.edu.cn> wrote:
>> >> > Hi,
>> >> > I am a new comer of JVM and Harmony. Since I have just learnt Harmony
>> for
>> >> a few time, I wonder whether Harmony(especially the VM) has implemented
>> or
>> >> has been interested in the features as follows.
>> >> > 1. SUN has proposed Java Isolation for a long while, and related
>> >> specifications have also been released. Unfortunately I cannot find any
>> >> support for it in SUN JVM till now. Has Harmony implemented or planned
>> to do
>> >> that? Or maybe SUN has implemented but I do not know it yet.
>> >>
>> >> [XF] I personally don't really see the needs to implement Isolation in
>> >> Harmony. But it is welcomed if anybody wants to have a try and I'd
>> >> like to help. I had some experience in it.
>> >>
>> >> > 2. Does SUN JVM or Harmony support to suspend, serialize and resume
>> the
>> >> JVM? In other words, a JVM can suspend the execution of itself and
>> >> bytecodes, transfer the execution status into an image file and resume
>> it
>> >> later. Assuming the external environments such as file system or network
>> >> connection still keeps.
>> >>
>> >> [XF] If I understand you correctly, the feature you described is the
>> >> fundamental feature of a JVM for garbage collection and exception
>> >> throwing. So all serious JVMs have it.
>> >>
>> >> > 3. Does the sandbox support appear as an independent project, or has
>> been
>> >> integrated in Harmony? Where can I find more documents about the sandbox
>> in
>> >> Harmony?
>> >>
>> >> [XF] I am not sure what you mean with sandbox. If you mean Applet
>> >> support, yes, Harmony has it (almost done).
>> >>
>> >> > In general, I want to know whether Harmony planned to be another (open
>> >> source) implementation of SUN JVM, or has its special features beyond
>> the
>> >> latter? I am not familiar with both SUN JVM and Harmony, so my question
>> may
>> >> be naive :)  Your kind and patient answers are appreciated.
>> >>
>> >> [XF] Please read some documents on Apache Harmony in its website. That
>> >> will help you to have a basic understanding. Harmony is an open source
>> >> Java SE implementation under Apache license. I personally think
>> >> Harmony wants to be compatible at first, and might have some special
>> >> features.
>> >>
>> >> Thanks,
>> >> xiaofeng
>> >>
>> >> > Thanks a lot!
>> >> >
>> >> >
>> >> >
>> >> >
>> >> > Rui Chu
>> >> >
>> >> >
>> >> >
>> >>
>> >>
>> >>
>> >> --
>> >> Managed Runtime Technology Center, Intel
>> >>
>> >>
>> >
>>
>>
>>
>> --
>> Managed Runtime Technology Center, Intel
>>
>



-- 
Managed Runtime Technology Center, Intel
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